A pregnant Los Angeles Chargers fan says a photo shows a Pittsburgh Steelers fan choking her on Sunday as the two teams faced off at Heinz Field.

Donna Bryan said the fan, who was not identified, shouted at her and her husband, Daniel Minshew, to sit down during the game.

It's not clear how things escalated from there, but an image captured by photographer Shelley Lipton shows the fan's hands around Bryan's neck.

Separate video appears to show Bryan with her hands around the fan's neck.

Bryan said her neck is bruised but she is doing fine.

No arrests have been made in the incident, though police are investigating.

In a statement, the Steelers said: “We strive to make events at Heinz Field safe for our guests. This type of behavior seen in the photo is unacceptable and something we do not condone on our property.

"We are working with Heinz Field security as well as local authorities to gather more information on this particular incident as the Pittsburgh Police determines whether or not to press charges, and we will ensure those involved as the aggressors will not be permitted back into our stadium.”